Performance Models

Abstract

Previous chapters have demonstrated the enormous amount of experimental research that has been done on pointing devices and human performance. We have seen the complex interaction between type of device, type of task, type of limb and type of user. We have derived Fitts’ law parameters and examined relationships between models of movement such as the SOS model and device type. As valuable as these studies are for a better understanding of device design and for the fundamentals of human psychomotor performance, they may be of little practical value to the ergonomics analyst who, during design of an interactive system, wishes to predict human performance in a situation of real use. For example, given a task in a 3D CAD/CAM design system such as inputting the parameters for the surface of an object, how long will it take to perform with a mouse? With a joystick? Empirically-based approximations called performance models, which are the topic of this chapter, attempt to answer these questions.